Question

An ecological group suspects lobsters are consuming dangerous levels of mercury in a region of the world. Dangerous levels of mercury are classified when they reach beyond 6.5 parts per million. A random sample of 25 lobsters in the region were tested and the data is shown in the stemplot.

An ecological group suspects lobsters are consuming dangerous levels of mercury in a region of the world. Dangerous levels of mercury are classified when they reach beyond 6.5 parts per million. A random sample of 25 lobsters in the region were tested and the data is shown in the stemplot.


Key 2/2= 2.2 parts per million
Part A: What proportion of the lobsters in the sample have dangerous levels of mercury in their systems? (4 points)

Part B: Construct and interpret a 95% confidence interval for the mean mercury levels of the lobsters if the sample of 25 lobsters has a mean mercury level of 5.05 parts per million and standard deviation of 1.45 parts per million. (6 points)

Answer 1

Given,

Confidence level = 0.95

Since, sample size is small (n < 30), so, t-interval will use

Degree of freedom (df) = n-1 = 25-1 = 24

Critical t value at 0.05 level of significance for 24 degree of freedom is 2.064

95% confidence interval for is,

For part (a) did not get what is "key 2/2 = 2.2"??